Continuous heating furnace



45 skilled in the'art.

Patented Dec. 25, 1928.

UNITED STATES PATENT OFFICE.

CHARLES E. LEHR, F BETHLEHEM, PENNSYLVANIA, ASSIGNOR TO BETHLEHEM STEEL COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTINUOUS HEATING FURNACE.

Application filed April 6,

The present invention relatesto continuous heating furnaces and particularly to furnaces designed and constructed especially for" nace at one end and removed in a heated; condition at the opposite end, the heated blanks being fed. immediately to therolling I 2 mill. In one instance this reheating ro'cess has been carried out ina furnace of t econ? tinuous type in which the heating flame'is projected into the combustion space or heatmg chamber at one end of the same, the;

2 cool blanks being inserted at the opposite end of the furnace and withdrawn from this chamber at the end adjacent the heating flame. The temperature of the blanks is thus raised gradually as they approach 3 the outlet end of thefurnace and they are withdrawn as soon as the desired tempera ture has been reached. Blanks having large surface areas in proportion to volumes are readily heated. As-the blanks approach the outlet end of the furnace however they come in direct contact with the heating flame and as a consequence the surface of the metal is oxidized and a scale formed thereon which is undesirable, causing not only a serious loss of weight of the blank,

especially where the blanks are of light weight and also objectionable in case the blanks are to undergo further rolling operations, as will be readily appreciated :by one The object of the present invention is to provide a continuousheating furnace particularly adapted for use in heating metallic blanks of the character 'ab'oveindicated and provided with means whereby oxidation of the surface of the blank and formationof' scale is prevented.

The invention may have various embodiments one of wh ch 1s illustrated in the ac 1923. Serial No. 630,327.

companying drawings and is herein described in detail. In the drawings:

Figure 1 is a vertical longitudinal section through the furnace;

Figure 2 is a section on line 2 2 of Fig-' ure 1, and

Figure?) is a section on line 33 of Figure 1.

The roof of the furnace is indicated at 10, the floor at 11 and the walls at the inlet and outgoing ends at 12 and 13 respectively. 'Two tiers of oil burners are indicated. at 14 and 1 1 respectively and are arranged to project flame into the heating chamber at one end thereof, the products of combustion being-withdrawn through the flue or down-' take '15 and thence conducted to a chimney (not illustrated). duced into the heating chamber through the openingv 16, whichmay' be closed between feeding-operations "by the door 17 and are removed through the openings 18 'at the op: posite end of the furnace the blanks sliding upon skids S a number of which are arrangedparallel and in the same plane, as can be seen from Figuresl and 2. These skids slope downwardly from the inletend. of the furnace to the outlet end to facilitate move- I ment'of' the blanks, which are merely pushed.

along these skids. Skids S are supported upon walls or piers P extending longitudinally of the furnace which piers are interrupted toprovide transverse openings 20 so that the hot products of combustion may c1rculate freely across the bottoms of the blanks. Toward the outletend of the'furnace the tops of the piers are connected by arches 21 which prevent the flame projected into the furnace by'the lower tire of burner nozzles from coming in contact with the The blanks are-,intro-' bottoms of the blanks, and above the skids at the outgoing endof the furnace a roof is provided which comprises'aiches 22- spring mg respectively from the side walls of the furnace and abutting at their inner ends upon a water cooled longitudinally extend- -ing. skew block 23 which is hung from the frame of'the furna'ceby water cooled pipes or suspending rods 24;

-Arches 22 serve to prevent the flame projected into the furnace from the upper tier of nozzles 14 from coming in direct contact with the blanks approaching this end of the furnace. The upper and lower arches therefore constitute muflle walls protecting the work within the muflle from flame contact. The skids S are continuous from one end of the furnace to the other but that portion of each skid which lies within the muille is solid and preferably ofnichrome while the remainder of the skid is hollow and water cooled, for instance being a pipe through which water is circulated. While the water cooled skids cool the blanks at the points of contact and thereby cause black spots to occur these spots are entirely eliminated during the passage of the blank through the inuflie so that upon being withdrawn they are found to be uniformly heated over their entire surfaces. As the flame of the burners cannot impinge directly upon the work oxidation is prevented saving iron which would otherwise be consumed by the flame and preventing the formation of scale.

To one skilled in the art the advantages of the invention will be apparent and it will also be obvious that the design of the furnace may be considerably modified without departing from the spirit and scope of the invention.

Having thus described theinvention what is claimed as n W and desired to be secured by Letters Patent'is: I

LA continuous heating furnace having a heating chamber provided with openings at opposite ends for the introduction and withdrawal of blanks, means to support said blanks in their travel through the furnace, ports disposed at the outlet end of the furnace so as to project the flame into the heating chamber from points above and below the said means and muflle Walls disposed above and below said. blank supporting means, whereby the blanks are shielded from direct contact with the flame.

2. A continuous heating furnace having inlet and exit openings for material, sources of heat arranged adjacent to the knit opening, skids extending longitudinally of the turnacc and shields for protecting the skids and the material supported thereon near the exit opening, each skid comprising a watercooled portion in the unshielded regions of the furnace and a solid portion in the shielded region.

A continuous heating furnace havinginlet and exit openings for material, sources of heat arranged adjacent to the exit opening, skids extending longitudinally of the furnace and shields for protecting the skids and the material supported thereon near the exit opening, each skid comprising a watercooled portion in unshielded regions of the furnace and a solid portion of heat resistant material in the shielded region.

in testimony whereof I hereunto atlix my signature.

CHARLES E. LEHR. 

